package com.loubobooo.personal.blog.util;

import java.io.IOException;
import java.io.StringWriter;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.JspFragment;
import javax.servlet.jsp.tagext.SimpleTagSupport;

public class HtmlFilterTag extends SimpleTagSupport {

    private static final int subLength = 100; //截取字符串长度

    private static final String regEx_script = "<script[^>]*?>[\\s\\S]*?<\\/script>"; // 定义script的正则表达式

    private static final String regEx_style = "<style[^>]*?>[\\s\\S]*?<\\/style>"; // 定义style的正则表达式

    private static final String regEx_html = "<[^>]+>"; // 定义HTML标签的正则表达式

    private static final String regEx_space = "\\s*|\t|\r|\n";//定义空格回车换行符

    public static String filter(String htmlStr) {
        Pattern p_script = Pattern.compile(regEx_script, Pattern.CASE_INSENSITIVE);
        Matcher m_script = p_script.matcher(htmlStr);
        htmlStr = m_script.replaceAll(""); // 过滤script标签

        Pattern p_style = Pattern.compile(regEx_style, Pattern.CASE_INSENSITIVE);
        Matcher m_style = p_style.matcher(htmlStr);
        htmlStr = m_style.replaceAll(""); // 过滤style标签

        Pattern p_html = Pattern.compile(regEx_html, Pattern.CASE_INSENSITIVE);
        Matcher m_html = p_html.matcher(htmlStr);
        htmlStr = m_html.replaceAll(""); // 过滤html标签

        Pattern p_space = Pattern.compile(regEx_space, Pattern.CASE_INSENSITIVE);
        Matcher m_space = p_space.matcher(htmlStr);
        htmlStr = m_space.replaceAll(""); // 过滤空格回车标签
        return htmlStr.trim(); // 返回文本字符串
    }

    @Override public void doTag() throws JspException, IOException {

        StringWriter sw = new StringWriter();
        JspFragment jf = this.getJspBody();
        jf.invoke(sw);
        String content = sw.getBuffer().toString();
        content = filter(content);
        content = content.replaceAll(" ", "");
        int contentLength = content.length();
        if (contentLength > subLength) {
            content = content.substring(0, subLength);
        }
        else {
            content = content.substring(0, contentLength);
        }
        ((PageContext) this.getJspContext()).getOut().write(content);
    }

}